shorters in strife with awe and bow

I see AWE had a large Short Sold position of 4.77mill sh's Tues or 56.9% of the 8.38mill traded on Tuesday.
Some 670k mimimum still have to be bought back on Thursday or Friday I suppose since only 4.1 mill. traded today.
BOW and STO also had huge short positions.

AWE LIMITED 8,384,658 Shares traded; 4,770,031 Shorts 56.89%
BOW ENERGY 3,965,069 Shares traded; 4,050,009 Shorts 102.14%
SANTOS 13,236,387 Shares traded; 8,925,182 Shorts 67.42%

Can anyone tell me when these positions have to be furnished with physical shares or can the funds/instos just keep borrowing our superfunds physical shares as proof of AWE shares held indefinitely.
Autosime, Entropylord anyone?